AlMgSi-BASED ALUMINUM ALLOY HAVING HIGH MACHINABILITY, MANUFACTURING METHOD THEREOF AND AUTOMOTIVE PARTS MANUFACTURED THEREFROM

ABSTRACT

The present invention relates to an AlMgSi-based aluminum alloy comprising 1.0-1.4 wt % of silicon (Si), 0.70-0.85 wt % of magnesium (Mg), 0.8-1.20 wt % of tin (Sn), 0.01-0.4 wt % of manganese (Mn), 0.001-0.50 wt % of iron (Fe), 0.01-0.10 wt % of copper (Cu), 0.01-0.25 wt % of chromium (Cr), 0.01-0.20 wt % of zinc (Zn), and the balance of unavoidable impurities and aluminum (Al), and to a manufacturing method thereof.

The present application claims priority under 35 U.S.C 119(a) to Korean Patent Application No. 10-2012-0128412 filed on Nov. 13, 2012 in the Korean Intellectual Property Office, which is incorporated herein by reference in its entirety set forth in full.

BACKGROUND

Exemplary embodiments of the present invention relate to an AlMgSi-based aluminum alloy, a manufacturing method thereof and automotive parts manufactured therefrom, and more particularly, to an AlMgSi-based aluminum alloy, which has improved machinability, can inhibit the occurrence of burrs, can minimize the possibility of breakage of a machining tool, can reduce the machining cycle time and can improve the quality of automotive parts, a manufacturing method thereof and automotive parts manufactured therefrom.

The ABS (antilock breaking system) or ESC (electronic stability control) pump housing is made mainly of 6000 series aluminum wrought alloys.

However, in the case of 6000 series aluminum wrought alloys, chips having long lengths are generally produced, and for this reason, curling of the chips is caused by a tool during machining, or load applied to a tool during machining is increased, and thus a machining failure is highly likely to occur. In addition, the machining speed can be reduced, and burrs can occur on the surface of the machined article, resulting in a reduction in the quality of the machined article.

Thus, there is a need for the development of aluminum alloy technology capable of improving the chip production process to minimize the machining cycle time and improve the quality of a machined part.

In connection with this, Korean Patent Laid-Open Publication No. 2008-0017374 (published on Feb. 26, 2008.02.26; entitled “Aluminum Alloy”) discloses an aluminum alloy comprising 4.5-6.5 wt % of magnesium, 1.0-3.0 wt % of silicon, 0.3-1.0 wt % of manganese, 0.02-0.3 wt % of chromium, 0.02-0.2 wt % of titanium, 0.02-0.2 wt % of zirconium, 0.0050-1.6 wt % of one or more rare earth metals, up to 0.2 wt % of iron, and the remainder of aluminum.

SUMMARY

An embodiment of the present invention relates to an AlMgSi-based aluminum alloy having improved mechanical properties and machinability.

Another embodiment of the present invention relates to an AlMgSi-based aluminum alloy having improved machinability, which reduces the machining cycle time to eliminate the occurrence of defects such as burrs on articles manufactured from the alloy, thereby improving the quality of automotive parts.

Still another embodiment of the present invention relates to a method for manufacturing said AlMgSi-based aluminum alloy, and automotive parts manufactured from said aluminum alloy.

In one embodiment, an AlMgSi-based aluminum alloy may include 1.0-1.4 wt % of silicon (Si), 0.70-0.85 wt % of magnesium (Mg), 0.8-1.20 wt % of tin (Sn), 0.01-0.4 wt % of manganese (Mn), 0.001-0.50 wt % of iron (Fe), 0.01-0.10 wt % of copper (Cu), 0.01-0.25 wt % of chromium (Cr), 0.01-0.20 wt % of zinc (Zn), and the balance of unavoidable impurities and aluminum (Al).

The content of manganese (Mn) in the aluminum alloy may be 0.01-0.35 wt %.

The content of the unavoidable impurities in the aluminum alloy may be 0.05-0.15 wt %.

The sum of the contents of silicon (Si), magnesium (Mg), tin (Sn) and manganese (Mn) in the AlMgSi-based alloy may be 3.0-3.3 wt %.

The sum of the contents of iron (Fe), copper (Cu), chromium (Cr) and zinc (Zn) in the AlMgSi-based alloy may be 0.01-0.5 wt %.

In another embodiment, a method for manufacturing an AlMgSi-based aluminum alloy includes: preparing a billet from an AlMgSi-based aluminum alloy composition, comprising 1.0-1.4 wt % of silicon (Si), 0.70-0.85 wt % of magnesium (Mg), 0.8-1.20 wt % of tin (Sn), 0.01-0.4 wt % of manganese (Mn), 0.001-0.50 wt % of iron (Fe), 0.01-0.10 wt % of copper (Cu), 0.01-0.25 wt % of chromium (Cr), 0.01-0.20 wt % of zinc (Zn), and the balance of unavoidable impurities and aluminum (Al), by a continuous casting process; and subjecting the prepared billet to homogenizing heat treatment, extrusion, stretching and aging heat treatment.

The content of manganese (Mn) in the aluminum alloy composition may be 0.01-0.35 wt %.

The content of titanium (Ti) in the AlMgSi-based aluminum composition may be 0 wt %.

The sum of the contents of silicon (Si), magnesium (Mg), tin (Sn) and manganese (Mn) in the AlMgSi-based aluminum alloy composition may be 3.0-3.3 wt %.

The sum of the contents of iron (Fe), copper (Cu), chromium (Cr) and zinc (Zn) in the AlMgSi-based aluminum alloy composition may be 0.01-0.5 wt %.

In another embodiment, automotive parts may be made of said AlMgSi-based aluminum alloy.

DESCRIPTION OF SPECIFIC EMBODIMENTS

Hereinafter, embodiments of the present invention will be described. However, the embodiments are for illustrative purposes only and are not intended to limit the scope of the invention.

In one embodiment of the present invention, an AlMgSi-based aluminum alloy may include 1.0-1.4 wt % of silicon (Si), 0.70-0.85 wt % of magnesium (Mg), 0.8-1.20 wt % of tin (Sn), 0.01-0.4 wt % of manganese (Mn), 0.001-0.50 wt % of iron (Fe), 0.01-0.10 wt % of copper (Cu), 0.01-0.25 wt % of chromium (Cr), 0.01-0.20 wt % of zinc (Zn), and the balance of unavoidable impurities and aluminum (Al).

Hereinafter, each of the elements in the AlMgSi-based aluminum alloy of the present invention will be described in detail.

The content of silicon (Si) in the AlMgSi-based aluminum alloy may be, for example, 1.0-1.4 wt %, for example, 1.2-1.4 wt %, for example, 1.21-1.4 wt %, for example, 1.22-1.4 wt %, for example, 1.23-1.4 wt %, for example, 1.24-1.4 wt %, for example, 1.25-1.4 wt %, for example, 1.2-1.3 wt %, for example, 1.21-1.3 wt %, for example, 1.22-1.3 wt %, for example, 1.23-1.3 wt %, for example, 1.24-1.3 wt %, for example, 1.25-1.3 wt %, for example, 1.21-1.29 wt %, for example, 1.21-1.28 wt %, for example, 1.21-1.27 wt %, for example, 1.21-1.26 wt %, for example, 1.21-1.25 wt %, for example, 1.2-1.25 wt %. If the content in silicon (Si) in the aluminum alloy is less than 1.0 wt %, the hardness of the alloy will be reduced, and if the content of silicon (Si) in the alloy is more than 1.4 wt %, the casting speed during a continuous casting process for preparing a billet will be reduced due to the high content of silicon (Si), resulting in a reduction in productivity, and the flow stress of the alloy during extrusion will increase, resulting in a reduction in the extrusion speed and a reduction in the surface quality of the alloy. In addition, the hardness of the alloy will be increased due to the influence of an excess of silicon (Si), resulting in an increase in the abrasion of a tool.

Magnesium (Mg) in the AlMgSi-based aluminum alloy reacts with silicon to form an intermetallic compound of Mg₂Si, which induces the strengthening of the alloy by precipitation. The content of magnesium (Mg) in the alloy may be, for example, 0.70-0.85 wt %, for example, 0.7-0.8 wt %, for example, 0.71-0.8 wt %, for example, 0.72-0.8 wt %, for example, 0.73-0.8 wt %, for example, 0.74-0.8 wt %, for example, 0.75-0.8 wt %, for example, 0.7-0.79 wt %, for example, 0.7-0.78 wt %, for example, 0.7-0.77 wt %, for example, 0.7-0.76 wt %, for example, 0.7-0.75 wt %, for example, 0.71-0.79 wt %, for example, 0.72-0.78 wt %, for example, 0.73-0.76 wt %, for example, 0.74-0.75 wt %. If the content of magnesium in the alloy is less than 0.70 wt %, the possibility of occurrence of adhesion between generated chips will be high, and Mn will precipitate with tin so that an MgSi precipitate (that strengthens the physical properties of the alloy) will be relatively reduced, resulting in deterioration in the physical properties of the alloy. If the content of magnesium in the alloy is more than 0.85 wt %, it will enhance the fibrous structure in the alloy matrix to increase the length of the chips while reducing the machinability of the alloy.

Tin (Sn) in the AlMgSi-based aluminum alloy reacts with magnesium to produce a magnesium-tin (Mg—Sn)-based precipitate, which can serve to break the chips during machining so as to improve the machinability of the alloy. Thus, the above property can be excessive or insufficient depending on the content of tin. Based on the results of observation of the shape and length of chips generated during machining, the content of tin in the alloy may be 0.8-1.2 wt %, for example, 0.8-0.9 wt %, for example, 0.8-0.89 wt %, for example, 0.8-0.88 wt %, for example, 0.8-0.87 wt %, for example, 0.8-0.86 wt %, for example, 0.8-0.85 wt %, for example, 0.81-0.89 wt %, for example, 0.82-0.86 wt %, for example, 0.83-0.87 wt %, for example, 0.84-0.86 wt %. If the content of tin is less than 0.8 wt %, the effect of improving the machinability of the aluminum alloy will be insufficient. If the content of tin is more than 1.20 wt %, the size of chips will be small, but the possibility of occurrence of damage to a tool during machining can be increased due to adhesion between the chips.

Manganese (Mn) in the AlMgSi-based aluminum alloy change needle-like β-AlFeSi to spherical α-AlFeSi to improve the extrudability and extruded surface of the alloy. For this purpose, the content of manganese in the alloy may be 0.01-0.40 wt %, for example, 0.3-0.4 wt %, for example, 0.31-0.39 wt %, for example, 0.32-0.38 wt %, for example, 0.33-0.37 wt %, for example, 0.34-0.36 wt %, for example, 0.3-0.35 wt %. If the content of manganese in the alloy is less than 0.01 wt %, the needle-like shape of compounds such as AlFeSi can be produced, and the grain refining effect can be insignificant. If the content of manganese is more than 0.40 wt %, the strength of the aluminum alloy can be reduced.

The sum of the contents of silicon (Si), magnesium (Mg), tin (Sn) and manganese (Mn) in the AlMgSi-based aluminum alloy may be 3.0-3.3 wt %, for example, 3.1-3.3 wt %, for example, 3.1-3.2 wt %, for example, 3.15-3.25 wt %. In this content range, the AlMgSi-based aluminum alloy can have improved mechanical properties and machinability. In addition, the AlMgSi-based aluminum alloy can have improved machinability, which reduces the machining cycle time to eliminate the occurrence of defects such as burrs on an article manufactured from the alloy, thereby improving the surface quality of the article.

Iron (Fe), copper (Cu), chromium (Cr) and zinc (Zn) in the AlMgSi-based aluminum alloy should be added as unavoidable impurities in the range that does not deteriorate the properties of the alloy. As the contents of iron, copper, chromium and zinc in the alloy, the properties of the alloy can be deteriorated. Specifically, the content of iron (Fe) in the alloy may be 0.50 wt % or less, for example, 0.001-0.5 wt %, for example, 0.1-0.3 wt %, for example, 0.15-0.25 wt %, for example, 0.2-0.25 wt %. The content of copper (Cu) in the alloy may be 0.10 wt % or less, for example, 0.01-0.1 wt %, for example, 0.01-0.05 wt %, for example, 0.01-0.04 wt %, for example, 0.01-0.03 wt %, for example, 0.02-0.04 wt %. The content of chromium (Cr) in the alloy may be 0.25 wt % or less, for example, 0.01-0.25 wt %, for example, 0.1-0.2 wt %, for example, 0.1-0.15 wt %, for example, 0.11-0.15 wt %, for example, 0.12-0.15 wt %, for example, 0.13-0.15 wt %, for example, 0.14-0.15 wt %, for example, 0.14-0.16 wt %. The content of zinc (Zn) in the alloy may be 0.20 wt % or less, for example, 0.01-0.2 wt %, for example, 0.01-0.1 wt %, for example, 0.01-0.09 wt %, for example, 0.01-0.08 wt %, for example, 0.01-0.07 wt %, for example, 0.01-0.06 wt %, for example, 0.01-0.05 wt %, for example, 0.01-0.04 wt %, for example, 0.01-0.03 wt %, for example, 0.01-0.02 wt %. In these ranges, the properties of the alloy cannot be deteriorated.

The sum of the contents of iron (Fe), copper (Cu), chromium (Cr) and zinc (Zn) in the AlMgSi-based aluminum alloy may be 0.01-0.5 wt %, for example, 0.1-0.5 wt %, for example, 0.1-0.4 wt %, for example, 0.35-0.45 wt %. In this range, the properties of the alloy cannot be deteriorated.

The content of titanium (Ti) in the AlMgSi-based aluminum alloy may be 0 wt %. The AlMgSi-based aluminum alloy of the present invention can ensure sufficient machinability, even if it contains no titanium.

The unavoidable impurities in the AlMgSi-based aluminum alloy can mean impurities contained in raw materials that are collected to obtain the above-described elements.

The content of each of the unavoidable impurities in the AlMgSi-based aluminum alloy may be 0.05 wt % or less, and preferably 0.01-0.05 wt %, and the sum of the contents of the impurities in the alloy may be 0.15 wt % or less, and preferably 0.05-0.15 wt %. In these ranges, the physical properties of the aluminum alloy cannot be deteriorated while the production of intermetallic compounds between different metals can be inhibited.

The inventive AlMgSi-based aluminum alloy comprising the above weight weights of elements has excellent mechanical machinability and strength, which can reduce the machining cycle time, and the improved machinability of the aluminum alloy can reduce the amount of burrs thereon.

In another embodiment, a method for manufacturing the AlMgSi-based aluminum alloy may comprises the steps of: preparing a billet from an AlMgSi-based aluminum alloy composition, comprising 1.0-1.4 wt % of silicon (Si), 0.70-0.85 wt % of magnesium (Mg), 0.8-1.20 wt % of tin (Sn), 0.01-0.4 wt % of manganese (Mn), 0.001-0.50 wt % of iron (Fe), 0.01-0.10 wt % of copper (Cu), 0.01-0.25 wt % of chromium (Cr), 0.01-0.20 wt % of zinc (Zn), and the balance of unavoidable impurities and aluminum (Al), by a continuous casting process; and subjecting the prepared billet to homogenizing heat treatment, extrusion, stretching and aging heat treatment.

In the above manufacturing method, the step of preparing the billet from the AlMgSi-based aluminum alloy composition by the continuous casting process, and the step of subjecting the prepared billet to homogenizing heat treatment, extrusion, stretching and aging heat treatment may be performed by methods known to those skilled in the art.

The aging heat treatment may be performed at various temperatures depending on the required physical properties of the alloy. Specifically, because the precipitation behavior of compounds by addition of tin varies, the heat treatment process may preferably be performed at a temperature of 130˜180° C., and more preferably 130˜150° C., in order to ensure a uniform distribution of precipitates and prevent coarse precipitates.

The details of each element in the above manufacturing method are as described above.

In another embodiment of the present invention, automotive parts may be made of the AlMgSi-based aluminum alloy. Examples of the automotive parts include, but are not limited to, an ABS pump housing, an ESC pump housing and the like.

Hereinafter, the construction and operation of the present invention will be described in further detail with reference to preferred examples. It is to be understood, however, that these examples are for illustrative purposes and are not intended to limit the scope of the present invention in any way.

The contents not described herein can be readily envisioned by those skilled in the art, and thus the detailed description thereof is omitted.

EXAMPLE 1 AND COMPARATIVE EXAMPLES 1 to 3

In order to evaluate the characteristics of aluminum alloys, aluminum alloy compositions having the components and contents (unit: wt %) shown in Table 1 below were prepared. Billets were prepared from the alloy compositions and subjected to homogenizing heat treatment, extrusion and stretching, followed by aging heat treatment at 150° C., thereby preparing specimens.

TABLE 1 Si Mg Sn Mn Fe Cu Cr Zn Al and impurities Example 1 1.25 0.75 0.85 0.35 0.20 0.03 0.15 0.02 Balance Comparative 1.0 0.55 1.0 0.005 0.20 0.03 0.15 0.02 Balance Example 1 Comparative 1.2 0.95 1.0 0.55 0.20 0.03 0.15 0.02 Balance Example 2 Comparative 1.2 0.55 1.0 0.55 0.20 0.03 0.10 0.02 Balance Example 3

The machinability and hardness of the prepared specimens were evaluated, and the evaluation results are shown in Table 2 below.

TABLE 2 Machinability Strength Example 1 Excellent (no chip Excellent curling, no tool (HB 104-110) breakage, and a small amount of remaining burrs) Comparative Moderate Insufficient (HB 88-90) Example 1 Comparative Insufficient (chip Moderate Example 2 curling occurred) (HB 102-105) Comparative Insufficient (breakage Moderate (HB 98-100) Example 3 of small-diameter drill)

As shown in Table 2 above, the aluminum alloy specimen according to the present invention had no chip curling, and no burr remains on the aluminum alloy specimen, suggesting that the aluminum alloy of the present invention has excellent machinability. In addition, the specimen of the present invention also had excellent strength.

However, in the case of the aluminum alloy of Comparative Example 1, which has a manganese content of less than 0.01 wt %, the possibility of production of the needle-like shape of compounds such as AlFeSi was high, and the grain refining effect was insignificant, resulting in a decrease in the hardness value of the alloy.

In addition, in the case of the aluminum alloy of Comparative Example 2, which has a magnesium content of more than 0.85 wt, the fibrous structure in the alloy matrix was strengthened to increase the length of the chips, and the effect of improving the machinability of the alloy was insignificant, resulting in the occurrence of chip curling.

In addition, in the case of Comparative Example 3, which has a magnesium content of less than 0.07 wt %, the adhesion of the generated chips increased while the breakage of a small-diameter drill occurred, and a precipitate with tin could be produced so that an MgSi precipitate (that enhance the physical properties of the alloy) was relatively reduced, resulting in deterioration in the physical properties of the alloy.

As described above, the embodiments of the present invention can provide the AlMgSi-based aluminum alloy having mechanical properties and machinability. In addition, the improved machinability of the AlMgSi-based aluminum alloy can reduce the machining cycle time to eliminate the occurrence of defects such as burrs on an article manufactured from the alloy, thereby improving the quality of the article.

The embodiments of the present invention have been disclosed above for illustrative purposes. Those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims. 

1. An AlMgSi-based aluminum alloy comprising 1.0-1.4 wt % of silicon (Si), 0.70-0.85 wt % of magnesium (Mg), 0.8-1.20 wt % of tin (Sn), 0.01-0.4 wt % of manganese (Mn), 0.001-0.50 wt % of iron (Fe), 0.01-0.10 wt % of copper (Cu), 0.01-0.25 wt % of chromium (Cr), 0.01-0.20 wt % of zinc (Zn), and a balance of unavoidable impurities and aluminum (Al).
 2. The AlMgSi-based aluminum alloy of claim 1, wherein the content of manganese (Mn) in the alloy is 0.01-0.35 wt %.
 3. The AlMgSi-based aluminum alloy of claim 1, wherein the content of the unavoidable impurities in the alloy is 0.05-0.15 wt %.
 4. The AlMgSi-based aluminum alloy of claim 1, wherein the content of titanium (Ti) in the AlMgSi-based aluminum alloy is 0 wt %.
 5. The AlMgSi-based aluminum alloy of claim 1, wherein the sum of the contents of silicon (Si), magnesium (Mg), tin (Sn) and manganese (Mn) in the AlMgSi-based alloy is 3.0-3.3 wt %.
 6. The AlMgSi-based aluminum alloy of claim 1, wherein the sum of the contents of iron (Fe), copper (Cu), chromium (Cr) and zinc (Zn) in the AlMgSi-based alloy is 0.01-0.5 wt %.
 7. A method for manufacturing an AlMgSi-based aluminum alloy, the method comprising: preparing a billet from an AlMgSi-based aluminum alloy composition, comprising 1.0-1.4 wt % of silicon (Si), 0.70-0.85 wt % of magnesium (Mg), 0.8-1.20 wt % of tin (Sn), 0.01-0.4 wt % of manganese (Mn), 0.001-0.50 wt % of iron (Fe), 0.01-0.10 wt % of copper (Cu), 0.01-0.25 wt % of chromium (Cr), 0.01-0.20 wt % of zinc (Zn), and the balance of unavoidable impurities and aluminum (Al), by a continuous casting process; and subjecting the prepared billet to homogenizing heat treatment, extrusion, stretching and aging heat treatment.
 8. The method of claim 7, wherein the content of manganese (Mn) in the aluminum alloy composition is 0.01-0.35 wt %.
 9. The method of claim 7, wherein the content of titanium (Ti) in the AlMgSi-based aluminum composition is 0 wt %.
 10. The method of claim 7, wherein the sum of the contents of silicon (Si), magnesium (Mg), tin (Sn) and manganese (Mn) in the AlMgSi-based aluminum alloy composition is 3.0-3.3 wt %.
 11. The method of claim 7, wherein the sum of the contents of iron (Fe), copper (Cu), chromium (Cr) and zinc (Zn) in the AlMgSi-based aluminum alloy composition is 0.01-0.5 wt %.
 12. An automotive part made of the AlMgSi-based aluminum alloy of claim
 1. 13. The automotive part of claim 12, wherein the content of manganese (Mn) in the alloy is 0.01-0.35 wt %.
 14. The automotive part of claim 12, wherein the content of the unavoidable impurities in the alloy is 0.05-0.15 wt %.
 15. The automotive part of claim 12, wherein the content of titanium (Ti) in the AlMgSi-based aluminum alloy is 0 wt %.
 16. The automotive part of claim 12, wherein the sum of the contents of silicon (Si), magnesium (Mg), tin (Sn) and manganese (Mn) in the AlMgSi-based alloy is 3.0-3.3 wt %.
 17. The automotive part of claim 12, wherein the sum of the contents of iron (Fe), copper (Cu), chromium (Cr) and zinc (Zn) in the AlMgSi-based alloy is 0.01-0.5 wt %. 